HYMENOPTERA (ICHNEUMONS, ETC.) 183 



claws, and taken by the mouth and mixed with saliva to form 

 a plastic substance from which the cells are moulded. Propolis 

 is the product of resinous substances off buds of trees, &c., 

 collected by the bees to use as cement, and to fill in crevices 

 between the irregular cells in the comb, and for the attachment 

 of the latter. 



The other group of this division, the Fossores, are the 

 Digging-wasps. Cerceris arenaria and Pomjnlius idumheus are 

 two common types. The former is black and yellow, the latter 

 red and black. They are lively solitary insects which hunt for 

 their prey. The females often dig a hole in the ground in 

 which to lay an egg ; in this is also placed a grub, to serve as 

 food for the newly hatched larva. The buried grub is not dead, 

 but paralysed by the sting of the Digging-wasp {Pomiyilius). 

 All being insectivorous, we may look upon them as beneficial 

 to us. 



Ichneumons, Gall-flies, &c. (Hymenoptera parasitica 

 or teretorantia). 



The chief families are — 



(i) The Chcdcididce, whose larvas are parasitic in various 



insect larvae and ova, and even in other parasites ; 



(ii) The Braconidce, which attack caterpillars and beetle- 



larvce ; 

 (iii) The Iclinewnonidce, which attack all larvee ; 

 (iv) Proctotrupidce — Larvae parasitic in eggs and bodies of 



other Arthropods ; and 

 (v) Cynipidm — Parasitic in plants, &c. 

 The ova laid by the various insectivorous insects hatch into 

 little grubs, which gradually devour their host, but not until 

 they and their host have nearly reached maturity, when they 

 pupate either within or external to their prey. Some, however, 

 oviposit in insect eggs. The little yellow cocoons we often see 



